1 year old purebred female German Shepherd

We are moving to a new place that we cannot take our 1year old female purebred German shepherd. My son paid $500 for her as a puppy and will include her $100 cage, any food we have and brushes and combs. She has papers to apply for her pure bred authenticity. All shots are up to date. She is a great dog and would be a great pet or good for breeding as well. He is asking $400 for her.